The rule regarding moving the guns so as to deliberately mislead the dog in their marking refers to relocating the guns to a position other than the one that they threw from. The rule has absolutely nothing to do with how they are seated 8)

I suppose that this one belongs in the "how dogs mark" category. I just don't buy into the theory that they way the gun is facing makes a hoot to the dog. If it does, then the dogs are concerned about the wrong thing.
I personally wouldn't face them the opposite way that they're throwing because of people's perception that they even notice such things. In my 30+ years of watching dogs in the field I don't believe that the dogs have any concept of anything except the presence of a person in a chair or on a 4 wheeler. We throw marks and sit on 4 wheelers most of the time, sometimes facing the line, sometimes perpendicular to the line. If the dogs were so intune to the way the gun was facing then it would be easy to deceive them. I think they mark the bird, or at the least a reasonable area of the fall.
Would it be possible to train them to only go to the side of the gun that the gunners are facing? Possibly, but why waste all that training time when 1/2 to 2/3 of the all-age marks are now retired.
I'm with Gerard, when judging I often have them sitting facing the line for the sake of visibility, not to try and influence them one way or the other.
Get down at dog level sometime, imagine that you're a dog. Take a look at that mark at 300 yards. What are you looking at before you're sent to retrieve? You're looking at where you think the bird is, not which way the gunner is seated. Heck, much of the time you might only see a little bit of white. The dog would have to be much closer to the gun to determine the seating arrangement. I would not think that at that point he/she would suddenly change thier mind about where they thought the bird was.
Just MHO based on oberserving lots and lots of dogs from the field (an excellent place to observe dog behavior I might add). I encourage everyone to watch their own dog from the field on a regular basis, you may learn something about them you'd never learn from watching them from the line.